August 16, 2009 in Idaho Voices

Sunspot activity can have a strong effect on climate

Michelle Boss

Has the sun been feeling a little less hot lately?

It might seem odd to ask that during what is usually the hottest part of the year. But the brightness of the sun is actually affected by things called sunspots – and like last year, they have been noticeably absent. Sunspots, dark spots on the sun which can span as much as 50,000 miles in diameter, are caused by magnetic storms.

The spots indicate areas of increased magnetic activity, which are commonly accompanied by solar flares. These flares can impact us on earth by disrupting communications equipment and electrical power grids. They are responsible for the spectacular bright auroras which can sometimes be seen across the Inland Northwest nighttime sky.

But changes in solar activity may also have an impact on climate. Though it may sound counterintuitive, the brightness of the sun actually increases (by about one-tenth of one percent) with increased sunspot activity. That may not sound like a large amount, but when you consider that the quantity of energy emitted from the sun’s surface is approximately 63 million watts per square meter, a small percentage of that is still a big number.

What is really interesting about sunspots is that they seem to run on a see-saw cycle of 11 years, a cycle which has been documented and studied since the 1800s. Activity peaks in the middle of that 11-year cycle, which was back in 2001. Scientist expected a new cycle to start last year, with sunspot activity peaking again sometime in 2012, but so far nothing is happening. The sun is as inactive as it was three years ago, and solar physicists don’t have an explanation. There have been periods in past history where the level of sunspot activity was unusually low. The most extreme case occurred during what’s known as the “Maunder minimum.” This was a period from about 1645 to 1715, which happened to coincide with the “Little Ice Age” during which much of the world was subjected to bitterly cold winters. Of course there is plenty of ongoing debate about how much influence sunspot activity has on global climate.

August is the peak month for “fire weather” across Eastern Washington and North Idaho. Locally, recent storms have brought some cooling rains that have made the first half of August a little less “parched” than usual. Regionally, Washington and Idaho were in pretty good shape as of last Wednesday, with only one active large (lightning-caused) wildfire in Yakima County which had burned a little more than 3,000 acres.

Michelle Boss can be reached at weatherboss@

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